The present invention is related to the ducts for the distribution of treated air (cooled or heated and even conditioned in terms of humidity, dust, smell etc.) from suitable air treating devices into the inner environment (compartments, pullmans etc.) of a railway vehicle within which the air has to be propagated.
Traditionally the ducts of the above-referenced type are constituted by tubes having a quadrangular cross section with outlet slits distributed over the length thereof, and provided with insulated walls so as to deaden the noise generated by the air flow under pressure, and further with inner baffles and/or shutters associated to the slits, the design of which is laboriously determined by means of empiric methods to the aim of correcting the effects deriving from the reduction of air pressure and speed between the initial and the final ends of the duct.
These ducts involve several inconveniences: firstly they have a relevant encumbrance, since the local flow rate of the air therewithin is directly bound to the air rate of flow delivered by the treatment apparatus and, therefore, the cross section thereof must be such as to guarantee a sufficiently low air speed. Secondly these known ducts are of a complicated construction, owing to the presence of the respective baffles and shutters. Lastly, in spite of the presence of these elements, these known ducts do not enable obtaining a uniform distribution of the air flow to the successive areas of the inner environment of the vehicle, and moreover this flow originates an annoying noise due to the outlet speed of the air through the slits of the duct.